Energy storage system and method to improve battery performance based on battery connections

ABSTRACT

A battery system and method may be shown and described. Two or more batteries may be connected in an identical configuration to an output device. The batteries may be controlled by a control unit or logic chip which may be configured to operate in two phases. In the first phase, the two or more batteries may be connected in series. In the second phase, the two or more batteries may be connected in parallel. Switches may be connected to the positive and negative terminals of the batteries to switch the configuration from series to parallel, and vice-versa. A control unit may switch between the two phases at any desirable frequency to produce a desired output voltage and amperage. The switching speed between the two phases may be any number of rotations per second.

CROSS-REFERENCE TO RELATED APPLICATION

The present patent application claims benefit and priority to U.S.patent application Ser. No. 16/574,218 filed on Sep. 18, 2019 and U.S.Provisional Patent Application No. 62/740,546 entitled filed on Oct. 3,2018 which is hereby incorporated by reference into the presentdisclosure.

FIELD

An energy storage system and a method to improve performance ofbatteries may be shown and described.

BACKGROUND

Series and parallel connections are commonly known in the field ofelectronics. Each type of connection has its own types of advantages anddisadvantages and are utilized for various purposes. Multiple powersupplies arranged in series may have a larger voltage, whereas multiplepower sources in parallel may increase the amperage but not the voltage.

For example, two 12V and 100 Ah batteries connected in series may havean output of 24V and 100 Ah. Comparatively, the same two batteriesconnected in parallel may have an output of 12V and 200 Ah. Thus, ifthese batteries were powering a device, the device can be powered withdouble the voltage (24V compared to 12V) in series, or, alternatively,the device may be powered at the same 12V voltage but for twice as longin parallel (200 Ah instead of 100 Ah).

Further, typical batteries or energy storage systems may not be chargedand discharged simultaneously. Thus, they may not be able to drive aload while also receiving charge. This can be problematic when an energystorage system is used with a renewable source. These systems oftenrequire a central controller to control the charging and discharging ofthe system.

SUMMARY

A battery system and method may be shown and described. Two or morebatteries may be connected in an identical configuration to an outputdevice. The batteries may be controlled by a control unit or logic chipwhich may be configured to operate in two phases.

In the first phase, the two or more batteries may be connected inseries. The negative terminal of the first energy storage unit may beconnected to the positive terminal of the second energy storage unit,and the positive terminal of the first energy storage unit may beconnected to the negative terminal of the second energy storage unit aswell as the output device.

In the second phase, the two or more batteries may be connected inparallel. The positive terminals of all the batteries may be connectedto one another, and the negative terminals may be connected to oneanother. The positive and negative terminals in a parallel connectionmay then connect to the output source in the same parallel manner.

Then, the control unit may switch between the two phases at anydesirable frequency to produce a desired output voltage and amperage.The switching speed between the two phases may be any number ofrotations per second.

BRIEF DESCRIPTION OF THE FIGURES

Advantages of embodiments of the present invention will be apparent fromthe following detailed description of the exemplary embodiments thereof,which description should be considered in conjunction with theaccompanying drawings in which like numerals indicate like elements, inwhich:

FIG. 1A is an exemplary embodiment of an energy storage system.

FIG. 1B is an exemplary embodiment of an energy storage system.

FIG. 2 is an exemplary embodiment of an energy storage system.

FIG. 3A is an exemplary embodiment of an output current signal waveform.

FIG. 3B is an exemplary embodiment of an output voltage signal waveform.

FIG. 4 is an exemplary embodiment of a method of implementing aswitching circuit.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the spiritor the scope of the invention. Additionally, well-known elements ofexemplary embodiments of the invention will not be described in detailor will be omitted so as not to obscure the relevant details of theinvention. Further, to facilitate an understanding of the descriptiondiscussion of several terms used herein follows.

As used herein, the word “exemplary” means “serving as an example,instance or illustration.” The embodiments described herein are notlimiting, but rather are exemplary only. It should be understood thatthe described embodiments are not necessarily to be construed aspreferred or advantageous over other embodiments. Moreover, the terms“embodiments of the invention”, “embodiments” or “invention” do notrequire that all embodiments of the invention include the discussedfeature, advantage or mode of operation.

An electric circuit with the advantages of both series and parallelcircuits may be shown and described in exemplary embodiments describedherein. By quickly switching between a series and parallelconfiguration, the circuit may output an average of the series andparallel outputs. The output of the switching circuit may be adjusted byadjusting the phase frequency, or amount of time between switches. Ahigher voltage may be achieved by increasing the amount of time thecircuit is in the first phase, when the circuit is in a seriesconfiguration. Alternatively, a higher amperage may be achieved byincreasing the amount of time the circuit is in the second phase, whenthe circuit is in a parallel configuration. A higher voltage may bedesirable for circuits powering larger loads, or a higher amperage maybe desirable in order to increase the amount of time a load is poweredfrom a battery. Since a circuit could be supplying electricity to anyone of multiple types of loads, it may be desirable to alter the voltageor amperage, depending on the load.

Referring now to exemplary FIG. 1A, a switching circuit may be shown ina parallel configuration. Two energy storage units, in this exemplaryembodiment a first battery 102 and a second battery 104, may beconnected by a set of switches. In this exemplary embodiment, thesebatteries may be wet-cell lead acid batteries of 12 volts and 100-amphours each. The positive and negative terminals of each battery may beconnected to switches. Switch 106 may permanently connect to thepositive terminal of battery 104 and may connect to the positiveterminal of battery 102 in the parallel phase. Thus, there may be a nodeat switch 106 connecting the positive terminals of battery 102, battery104, and the positive terminal of the output.

Still referring to the parallel phase in exemplary FIG. 1A, anadditional switch 108 may connect to the negative terminal of battery104. During the parallel phase, switch 108 may be configured to connectto the negative terminal of battery 102. Thus, there may be a node atswitch 108 connecting the negative terminals of the batteries 102 and104. Further, the output may be connected to switches 110 and 112. Inthe parallel phase, switch 110 may be configured to connect the output120 to the node created by the positive terminals of battery 102 andbattery 104. At the same time, switch 112 may be configured to connectthe negative terminal of output 120 to the node created by the negativeterminals of battery 102 and battery 104. Thus, the positive terminalsof the batteries and the positive terminal of the output are allconnected, and the negative terminals of the batteries and the negativeterminal of the output are also connected, and a parallel circuit may beformed.

Now referring to exemplary FIG. 1B, the circuit may be shown in a seriesconfiguration. The series configuration may take place in a differentphase than the parallel configuration. In the series configuration, theswitches 106, 108, 110, and 112 all be switched in the oppositedirection of the previous phase. The switches may be connected such thatthey may switch simultaneously. To form the series configuration, switch106 and switch 110 may connect the positive terminal of battery 104directly to the output 120. The negative terminal of battery 104 may beconnected to the positive terminal of battery 102, via switch 108. Thenegative terminal of battery 102 may be connected to the output 120 viaswitch 112. The switches may be any one of many types of switches orinterrupters. The switches may be flipped, or commuted, at the sametime. The output signals (current and voltage) may depend on thecommuting or switching time between the two phases.

Referring now to exemplary FIG. 2 , an electrical assembly may be shownwith an output 122 which may be configured to connect to the circuitonly during the series phase, and another output 124 which may beconfigured to connect to the circuit only during the parallel phase.This may be accomplished using the switches 114 and 116, which may beconfigured to switch at the same time as the other switches.

Still referring to the exemplary embodiment in FIG. 2 , the secondaryoutput 124 may be disconnected from the circuit during the parallelphase. If, for example, the output 124 is an energy storage system thatis charging from the switching circuit 100, it may continue to operatenormally during the parallel phase and may be charged only in the seriesphase.

An exemplary embodiment for the purposes of analysis, such as theembodiment in FIG. 2 , may include a battery or batteries with a nominalvoltage value of V_(n) and nominal current value of I_(a). The load ofoutput 122 during the parallel phase may beZ_(parallel)=(2*V_(n))/I_(n).

In an exemplary embodiment, t₁ may be the time spent in a first,parallel phase and t₂ may be the time spent during the second, seriesphase. Further, the time T may represent the period corresponding to thefundamental frequency, so T=1/fundamental frequency=t₁+t₂. If f(t) mayrepresent the input signal, the mean value of a signal may then becalculated using the formula:

$\begin{matrix}{{{Mean}( {f(t)} )} = {\frac{1}{T}{\int_{({t - T})}^{t}{{f(t)} \cdot {dt}}}}} & ( {{Equation}1} )\end{matrix}$

This formula may produce an exemplary output signal as shown inexemplary FIG. 3 . The output signal, as illustrated in FIG. 3 , may bea square signal. FIG. 3A may be the output of an exemplary currentsignal. FIG. 3B may be the output of an exemplary voltage signal. Thewidth of the horizontal line 302 may correspond to the time t₁. Thewidth of horizontal line 304 may correspond to the time t₂. Further, theintegral of the current (I) of the exemplary signal may produce thefollowing equations:

$\begin{matrix}{{\frac{1}{T}{\int_{0}^{t_{1}}{I_{1} \cdot {dt}}}} + {\frac{1}{T}{\int_{t_{1}}^{t_{1} + t_{2}}{I_{2} \cdot {dt}}}}} & ( {{Equation}2} )\end{matrix}$ $\begin{matrix}{{= {{\frac{1}{T} \cdot I_{1} \cdot t_{1}} + {\frac{1}{T}{I_{2} \cdot t_{2}}}}}{{The}{integral}{of}{the}{voltage}{signal}{may}{be}:}} & ( {{Equation}3} )\end{matrix}$ $\begin{matrix}{{\frac{1}{T}{\int_{0}^{t_{1}}{V_{1} \cdot {dt}}}} + {\frac{1}{T}{\int_{t_{1}}^{t_{1} + t_{2}}{V_{2} \cdot {dt}}}}} & ( {{Equation}4} )\end{matrix}$ $\begin{matrix}{= {{\frac{1}{T} \cdot V_{1} \cdot t_{1}} + {\frac{1}{T}{V_{2} \cdot t_{2}}}}} & ( {{Equation}5} )\end{matrix}$

Additionally, there may be a case where t₁=t₂. In this exemplary case,the mean value of the current may be found by the following equation:(I₁+I₂)/2, and the mean value of the voltage may be found by: (V₁+V₂)/2.

In the previously described exemplary embodiment, each battery may havea nominal current of 100 A and a nominal voltage of 12V. The combinedvoltage when the circuit is in series may be 24V and the combinedcurrent when the circuit is in parallel may be 200 A. As a result, thecurrent mean value may be 150 A and the voltage mean value may be 18Vwhen the circuit is switching between the first phase and the secondphase at an equal rate, i.e. the first phase and the second phase are ofequal lengths of time. In another exemplary embodiment, the time spentin the parallel phase (t₁) and the time spent in the series phase (t₂)may be altered such that they are unequal. For example, if t₁ istwo-thirds (⅔) of the cycle, and the same nominal voltage and current isused, the current mean value may be 166.666 A and the voltage mean valuemay be 16V. Alternatively, if t₁ is one-third (⅓) of the cycle, thecurrent mean value may be 133.3333 A and the current mean voltage may be20V. Any ratio of t₁ to t₂ may be used to achieve a desired result.

In a further exemplary embodiment, the circuit may be adjusted by acontrol unit capable of altering the frequency of the phases. Thecontrol unit may be able to set the switching speed or the switchingtime between the two phases. The switching time may be the amount oftime spent in each phase. The control unit may select a switching timebased on rotations per second, or any other measurement of time. Theremay be any number of switches or rotations per second, from 1 toinfinity. The control unit may configure the circuit to be in one phasemuch longer than the other phase. The phases may not be in equallengths. By changing the relative proportion of time spent in thephases, the output signal may be altered. Additionally, the control unitmay be set to initially keep the circuit in a specific state. Forexample, the control unit may be configured to start in the parallelphase until the energy storage units become fully charged. The controlunit may then begin the cycle of switching.

The batteries may be connected to an energy source. The circuit may beconfigured such that the batteries are connected in series during afirst phase, during which they may be connected to a load and may bedischarging. Then, during a second phase, the batteries may be connectedin parallel as well as to the energy source which may charge thebatteries during this phase. Thus, the batteries may discharge duringthe first series phase and charge during the second parallel phase.During the first cycle, the battery may discharge a small amount ofenergy. Further, during the second cycle a similarly small amount ofenergy may be charged to compensate for the energy lost during the firstcycle. This may improve battery performance.

The energy source may be chosen to have a larger current output so thata larger amount of energy is charged to the battery during the parallelphase. In an exemplary embodiment, the amount of charge from the energysource during the parallel phase may exceed the amount of chargedischarged by the load during the series phase, so the batteries maygain charge over time. It may be contemplated that when the batteryreaches a certain level, the excess charge is prevented from reachingthe battery in order to reduce the risk of overcharging. In an alternateembodiment, an energy source may be chosen which charges an amount ofenergy equal to the amount discharged during the series phase. In thisalternate exemplary embodiment, the energy storage units may constantlyhold the same amount of charge.

Additionally, by charging and discharging the batteries during theseshort cycles, the circuit may have the effect of charging anddischarging the batteries or energy storage systems at the same time.Typical batteries or circuits cannot charge and discharge simultaneouslyand instead may utilize a central controller to manage the charge anddischarge cycles. Typical energy sources may be connected directly tothe load or connected to an energy storage system but may not beconnected to both. As a result, the energy source may be configured toeither charge a battery or to drive a load, but not both. An exemplaryembodiment of a simultaneous series and parallel circuit as describedhere may be configured such that an energy source is connected to anenergy storage system which then may drive a load at the same time. Theload may draw power from the battery during a first phase and the energystorage system may charge during the second phase.

The energy source may be any type or combination of energy sources. Inan exemplary embodiment, a renewable energy source may be used, althoughit is envisioned that other energy sources may be utilized, as desired.

Now referring to exemplary FIG. 4 , a method for implementing aswitching circuit, such as the circuit in FIG. 2 , may be shown. In afirst step, the first phase may begin 400. The control unit may beginthe first phase by sending a signal to the switches. In the next step,the switches may be flipped 402 such that the circuit is switched to aseries configuration. The control unit may flip the switchessimultaneously. The switches may be connected to one another such thatthey are flipped at the same time. In a third step, the energy storageunits (ESUs) may charge the load 404. The load may be a rechargeablepower source.

In a fourth step, the second phase may begin 406. The control unit maybe configured to start the second phase after a certain amount of time,depending on how long the first phase is. The first phase and secondphase may be of different durations. In a next step, the switches may beflipped 408. During this step, the switches may be flipped to theopposite position that they were flipped to in step 402. The switchesmay be flipped such that the ESUs and the load are connected in aparallel configuration. In a final step, the energy source may chargethe ESUs 410. In an alternate embodiment, the ESUs may continuedischarging during the 2^(nd) cycle, in the parallel phase. In thisexemplary embodiment, the control unit may configure the ESUs tocontinue discharging so that they are connected to the load during bothphases. The energy source may be connected to a switch which connectsthe energy source to the circuit during the second phase and connectsthe load to the circuit during the first phase. This switch may also becontrolled by the control unit and may be flipped at the same time asthe other switches. After a predetermined period of time, the firstphase may once again begin 400 and a new cycle may start.

Although the previous examples may implement a switching circuitinvolving two batteries, it may be contemplated that the batteries mayinstead be any component that a user desires to be switched betweenseries and parallel. Further, two batteries were used in the previousexamples for the sake of clarity, but any number of batteries may beinterconnected in a similar manner. The additional batteries may beconfigured to operate in additional (more than two) phases. The outputmay be any desirable output, such as another battery, an energy storagesystem, or any other electrically connected component capable ofreceiving an input.

In an exemplary embodiment, the switching circuit may be implemented inan electric vehicle. The switching circuit may be configured such thatthe electric vehicle is powered during one phase and disconnected andcharging during the other phase. In an exemplary embodiment, the sameamount of energy discharged during the first phase may be charged duringthe second phase. During the powered phase, the battery may expendadditional energy to compensate for the energy lost during the unpoweredphase. However, since the battery may be activated for half the time(one out of two phases as opposed to a constant output), efficiency maybe increased.

Further, the switching circuit may allow for multiple sources of energyto be used simultaneously. For example, an electric vehicle powered byphotovoltaic cells may be charged using an alternate source of energy(such as wind, gas, etc.) during solar intermittencies.

The foregoing description and accompanying figures illustrate theprinciples, preferred embodiments and modes of operation of theinvention. However, the invention should not be construed as beinglimited to the particular embodiments discussed above. Additionalvariations of the embodiments discussed above will be appreciated bythose skilled in the art.

Therefore, the above-described embodiments should be regarded asillustrative rather than restrictive. Accordingly, it should beappreciated that variations to those embodiments can be made by thoseskilled in the art without departing from the scope of the invention asdefined by the following claims.

The invention claimed is:
 1. A system comprising: a first energy storageunit with a first positive terminal and a first negative terminal; asecond energy storage unit with a second positive terminal and a secondnegative terminal; a series configuration output; a parallelconfiguration output; a control unit configured to regulate a cyclecomprising a first phase and a second phase, wherein during the firstphase, the first negative terminal is connected to the second positiveterminal while the first positive terminal and the second negativeterminal are connected to the series configuration output, such that thefirst energy storage unit, the second energy storage unit, and theseries configuration output are connected in series, wherein during thesecond phase, the first positive terminal is connected to the secondpositive terminal while the first negative terminal is connected to thesecond negative terminal, both positive terminals are connected to theparallel configuration output, and both negative terminals are connectedto the parallel configuration output, such that the first energy storageunit, the second energy storage unit, and the parallel configurationoutput are connected in parallel; and a plurality of switches, whereineach switch of the plurality of switches is configured to be connectedto the energy storage units in a series configuration during the firstphase and in a parallel configuration during the second phase, thecontrol unit is configured to set relative durations of the first phaseand the second phase and determine an output as a weighted averagebetween the series configuration output and the parallel configurationoutput, and the weighted average is weighted based on the relativedurations of the first phase and the second phase.
 2. The system ofclaim 1, wherein the control unit is one of a programmable mechanical,electronic, PCB or integrated circuit chip.
 3. The system of claim 1,wherein the series configuration output comprises a load and theparallel configuration output comprises an energy source.
 4. The systemof claim 1, wherein the first energy storage unit and the second energystorage unit each comprise a plurality of batteries.
 5. The system ofclaim 1, wherein the duration of the first phase is equal to theduration of the second phase.
 6. The system of claim 1, wherein thefirst energy storage unit and the second energy storage unit arecapacitors.
 7. The system of claim 1, further comprising: a rechargeablepower source, wherein, during the second phase, the control unit isfurther configured to connect the positive terminals of the energystorage units to a positive terminal on the rechargeable power sourceand the negative terminals of the energy storage units to a negativeterminal on the rechargeable power source.
 8. The system of claim 7,wherein, during the first phase, the rechargeable power source isconfigured to drive a load.
 9. The system of claim 8, wherein an amountof energy is lost from the energy storage units to the load during thefirst phase and then recharged to the rechargeable power source duringthe second phase.
 10. The system of claim 1, wherein each switch of theplurality of switches is configured to be activated simultaneously. 11.The system of claim 1, wherein the control unit is configured to controlthe plurality of switches.
 12. The system of claim 1, wherein the energystorage units are configured to be initially in a fully charged state.13. The system of claim 1, wherein the control unit is configured tooperate more than one cycle per second.
 14. A circuit comprising: afirst energy storage unit with a first positive terminal and a firstnegative terminal; a second energy storage unit with a second positiveterminal and a second negative terminal; terminal; a seriesconfiguration output; a parallel configuration output; an outputterminal; a control unit that is configured to control a plurality ofswitches to regulate a cycle comprising a first phase and a secondphase, wherein during the first phase, the first negative terminal isconnected to the second positive terminal while the first positiveterminal and the second negative terminal are connected to the outputterminal, such that the first energy storage unit, the second energystorage unit, and the output terminal are connected in a series, whereinduring the second phase, the first positive terminal is connected to thesecond positive terminal while the first negative terminal is connectedto the second negative terminal, both positive terminals are connectedto the output terminal, and both negative terminals are connected to theoutput terminal, such that the first energy storage unit, the secondenergy storage unit, and the output terminal are connected in parallel;and the plurality of switches, wherein each switch of the plurality ofswitches is configured to be connected to the energy storage units andthe output terminal in a series configuration during the first phase anda parallel configuration during the second phase, the control unit isconfigured to alter relative durations of the first phase and the secondphase and determine an output of the output terminal as a weightedaverage between the series configuration output and the parallelconfiguration output, and the weighted average is weighted based on therelative durations of the first phase and the second phase.
 15. Thecircuit of claim 14, wherein each switch of the plurality of switches isconfigured to change position simultaneously.
 16. The circuit of claim14, wherein the output terminal further comprises a switch that isconfigured to switch between two or more output devices every phase. 17.The circuit of claim 14, wherein the control unit is further configuredto alter the relative durations to produce a specific output voltage anda specific output current.
 18. The circuit of claim 14, wherein eachswitch of the plurality of switches is a transistor.